Driving forces in the development of ultrasound imaging technology include the need for point-of-care imaging (e.g. by general practitioners or other deliverers of primary healthcare) and the introduction of clinical applications requiring three dimensional (3D) and four dimensional (4D) ultrasound imaging. As a result, there are trends towards the use of ultrasound probes with two dimensional (2D) arrays of ultrasound sensor elements and the miniaturization of probes through closer integration of the transducer and control electronics.
U.S. Pat. No. 4,694,434 describes an ultrasound imaging device with a 2D array of transmit and receive elements that is capable of generating 3D images. More recently, “Integration of 2D CMUT Arrays with Front-End Electronics for Volumetric Ultrasound Imaging”, Wygant et al (2008) describes an ultrasound imaging device with a 2D transducer array integrated on a silicon integrated circuit.
US Patent Application 2012/0144920 describes an ultrasound imaging device utilizing thin-film transistors to form an array of receive circuits.
WO2007/095390 proposes a TFT device with an integrated piezo-electric layer to generate or receive ultrasound signals, and also proposes an array comprising elements each containing one of these devices and a TFT switch.
GB2453695 proposes an ultrasound array with TFT devices, and suggests a TFT as a switch or amplifier in each element of the array.